Hey Sablesurfer, did you use soapy water to highlight that leak in #38, or did it bubble like that all on its lonesome?
I think I have figured a few things out. First, the guy on Redit who reported his bag splitting from the pressure of carbing his homebrew was using the standard cap, and not the cap with the connectors. That latter cap has a release valve. So, he must have been using sugar, and not the CO2 tank. The bag split because the normal cap has no way to release excess pressure.
Second, it looks like CO2 leaks are possible almost anywhere in the system. The two ends of the hose are only the most obvious choice. You also need to make sure the connector snaps onto the fitting good and square or it can leak from there. Also, if you do not screw the cap on squarely, it can leak from there. Finally, if you are especially unlucky, you may even be able to get a leak from the brass screw-on regulator fitting. Or at least it seems to screw on differently from one time to the next.
I re-used a bag and filled it with as much of my latest APA as I could get into it without owning the filler kit. I think I got more than three quarts, but who knows. I hooked the bag up to the CO2 tank with the pressure turned up as high as it would go, and set the temp at 32F. Pressure is always somewhere in the Medium range. I find if it drops down a little, that I can turn the regulator off and then back on again to get a small boost in pressure. I don't think this means I have a leak, but I am really not sure about that.
Anyway, it takes its own sweet time carbing up. Yesterday was day 9, and after taking smallish samples in previous days, I decided to take a full pour. I sat the glass down (no tilting or pouring down the side to reduce foaming) and set the Perlick to pour at full pressure - which was not a whole lot. By the time the glass filled I had a little over an inch of head. I am going to leave it connected over the weekend before trying again, but it was not too bad last night. The big problem is that the best temp for forced carbing (32F) is not a great temp for drinking an APA. I let it sit to warm up a bit, but that meant the head dissipated.
I think I will turn the temp up to about 40F for the weekend, so that the next pour is closer to drinking temp. Synek is sorta working for me, but I don't know that I'd recommend it to others.
One other thing: How much brew gets left in the bottom of the bag depends on just how far the dip tube winds up from that bottom. It naturally wants to curl up a little, and if you let it slide to the left or the right, rather than pointing straight down, it will be that much further from the bottom. The problem is that it is very hard to tell just how close to the bottom you are. I suspect that if you fill using the filler kit, then you can feel where the hose is before you add the beer. I did not yet have the kit when I filled mine, so I could not really tell how close to the bottom it got. I guess I will find out soon enough.